organization of the petroleum exporting countries. (2017). annual report 2017. grasl druck & neue medien gmbh.
Lua i Stíl Chicago (17ú heag.)organization of the petroleum exporting countries. Annual Report 2017. austria: grasl druck & neue medien gmbh, 2017.
Lua MLA (9ú heag.)organization of the petroleum exporting countries. Annual Report 2017. grasl druck & neue medien gmbh, 2017.